Currently, methods for improving monoclonal antibody production on a cellular level are labor intensive and unreliable. The research proposed provides an automated approach to cell cloning, permitting the isolation of cells based on specific cellular functions. Individual hybridoma cells will be encapsulated into gel microdrops (GMDs), and secreted protein will be detected using a solid phase immunofluorescent assay performed within the GMD. GMDs containing single cells and exhibiting increased levels of fluorescence will be identified and isolated by flow sorting. This assay has been used to rapidly identify secreting cells from nonsecretors. The goals of the Phase I research are to: (1) evaluate the ability of this assay to discriminate between hybridoma cells with different secretory rates, (2) optimize the assay for maximal discrimination between hybridoma cells with different productivities, and (3) define conditions for isolation of GMDs by flow sorting. These experiments will form the basis for a rapid methodology for cell cloning with wide application in the research and in the industrial sectors.